Growth Response And Efficient Utilization Of Water And Fertilizer Of Young Apple Trees Under Alternate Drip Irrigation And Fertilization In Loess Plateau

Shanxi is located in the eastern part of the Loess Plateau.It is one of the most suitable areas for apple cultivation in China.However,the shortage of water resources and low fertilizer utilization rate restrict the quality development of the apple industry in the region.How to coordinate the use of water and fertilizer in orchard and improve the efficiency of water and fertilizer use is of great significance to the local ecology and economy.Alternate root-zone irrigation is a new type of water-saving technology which regulates the plant to improve water use efficiency.Drip fertigation is a water-and fertilizer-saving irrigation method,which can transfer liquid fertilizer directly and evenly to the crop root zone according to the requirement.The combination of alternate irrigation and drip fertigation has the potential of saving fertilizer and improving fertilizer use efficiency.Therefore,the effects of different fertilizer rates on the growth of young apple trees were studied in this study.In this experiment,one-year-old red Fuji apple young tree was used as the experimental object.Seven treatments were set up,including simultaneous drip irrigation and fertilization(N:P:K=300:300:150 kg/hm~2,CK)on both sides;and six alternative drip fertigation treatments(the fertilizer amounts were 0%(S1)?25%(S2)?50%(S3)?75%(S4)?100%(S5)?125%(S6)of CK).The effects of different fertilization levels on soil moisture and nutrient transport under CK treatment and alternate drip irrigation were analyzed,and the growth response of young apple trees to water and fertilizer conditions of was analyzed.The mechanism of the effect of alternate drip irrigation on fruit growth was revealed,and a high-quality and high-efficiency drip fertilization system was put forward,which was suitable for the growth of young apple trees in this area.The main conclusions are as follows:(1)The soil moisture in the soil surface(0-20 cm)is greatly influenced by the external environment,and the soil moisture changes greatly.The soil moisture increases with the increase of soil depth,while the soil nutrient content is higher in the soil surface layer(0-20 cm),and as the soil depth increases,the nutrient content is reduced.The content of available potassium in soil was the highest in 10-20 cm soil layer,but it changed little in 20-80 cm soil layer.The soil nitrate nitrogen content varies greatly in the 0-60 cm soil layer,and the change is gentle in the soil layer of60-80 cm.(2)After a turn of drip irrigation and fertilization(Four weeks),the distribution of soil moisture content?soil nitrate nitrogen content?soil ammonium nitrogen content and soil available potassium content in both sides of root zone under CK treatment were more uniform,however,the first side of the drip fertilizationwas lower than the second side of the drip fertilization under alternate drip fertigation treatments,due to the utilization and loss of water and nutrients on the first side were higher than the second side.(3)Alternate drip irrigation and fertilization can stimulate new shoots of fruit trees,and S4 has the most significant stimulation to the new shoots,the new shoots have the longest length.The increase of shoot coarseness of CK was higher than that of other treatments at each stage.Simultaneous drip fertilization on both sides was beneficial to the increase of shoot coarseness of young fruit trees,but there was no significant difference between CK and S4 in the new shoot coarseness of fruit trees in each period(p<0.05).(4)The low fertilizer application rate under S1-S3 treatments could not meet the growth requirement of young apple trees,and the growth of young apple trees was not as good as that of other treatments.S5 and S6 treatments did not significantly improve all growth indexes(p<0.05).The irrigation amount of CK was 50%more than S1-S6treatments,but its soil moisture content was not higher than that of all other treatments.At the same time,there was no significant difference in most growth indexes of apple saplings at the same period under CK and S4 treatment(p<0.05).Most of the growth indexes under S4 were significantly higher than other treatments.The results showed that S4(225:225:112.5 kg/hm~2)treatment could meet the growth requirements of young apple trees and achieve the goal of saving water and fertilizer.